I find it easier to step the mast with the boat sitting on the ground, off the trailer. When the boat's on the ground, the mast starts off at a higher angle (assuming you have someone holding up the mast tip, or you prop it up on something) so you don't have to bend over as far to get it started.

1) I park on a pretty steep ramp, pointing downhill.2) Let both sides of the shrouds out to their longest adjustment3) get the mast ready to raise, with step pin in place.4) Use a tall step ladder, walk around behind the boat and put the ladder under the mast... this will give you a "head start" on the dead-lift. (A friend of mine actually built an extra tall mast caddie for this purpose that fit right in where his trailering mast caddie went)5) If you have a second person have them pull on the forestay/bridal wires to help you lift.

I can still do it by myself, but I'm very careful and prefer a second helper...